Countertop oven



FIG. 1 is a top perspective view of the countertop oven showing the new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a right side elevational view thereof, the left side being a mirror image; and,

FIG. 4 is a top plan view thereof. 

The ornamental design of countertop oven, as shown and described. 